1. Field of the Invention
The present invention relates to a filter and a filter assembly.
2. Description of the Related Art
There has conventionally been proposed a filter created with the thickness of the wall part between through holes based on pore distribution. For example, the filter described in JP-A 2001-269522 is adapted to have a wall thickness T of 100 μm or more when P1 is 10%, while a wall thickness T of 300 μm or more when P1 is 30%, that is, to satisfy P1×10≦T, where P1 represents the ratio of pores with a pore diameter of 30 μm or more to the total pore volume while T represents the wall thickness. The filter is also adapted to have a wall thickness T of 150 μm or less when P3 is 10%, while a wall thickness T of 50 μm or less when P3 is 30%, that is, to satisfy (1/P3)×1500≧T, where P3 represents the ratio of pores with a pore diameter of less than 3 μm to the total pore volume while T represents the wall thickness. Thus, the prior arts mention that, in a filter including many pores with a large pore diameter, the wall thickness is increased to improve the filtering efficiency against particulate materials, while including many pores with a small pore diameter, the wall thickness is decreased to reduce pressure loss.